1. Field of the Invention
This invention relates to a method for separating veins from the lamina of the tobacco leaf. More particularly, this invention relates to a process for improving the fill power of tobacco in a cigarette product by removing the veins from the lamina.
2. Description of the Prior Art
In the processing of tobacco leaves for use in cigarettes, it is common for the leaf of tobacco to be run through a series of milling devices wherein the stem of the tobacco is removed from the lamina which includes the small vein portions therein. (As used hereinafter "stem" refers to the main stem or rib which extends through the individual pieces of lamina, and "vein" refers to the short stem pieces that are attached to the main stem or rib.) In the aforementioned processing of the leaf, milling devices are used with a classifying or a screening device disposed downstream after each milling operation wherein the lamina, including the veins, are caught in one section and the tobacco stems are caught in another section for further processing. The lamina, including the veins, are then generally further processed for use in the manufacture of cigarettes. In the further processing of the lamina, which includes the veins, the bulk lamina is generally cut into small pieces wherein the veins remain for use in cigarettes. These veins, when the lamina is cut, add density to the "fill power" of the tobacco and furthermore give a "birds eye" appearance in the small pieces of lamina, the "birds eye" being a portion of the lamina as seen along the axial cut of the vein.
In the prior art, U.S. Pat. No. 3,074,415; U.S. Pat. No. 3,126,014; New Zealand Pat. No. 139,007; and, U.S. Pat. No. 3,367,342, describe different methods and apparatuses for size reduction by threshing to remove large stems. And, U.S. Pat. No. 4,074,722 teaches a process for manufacturing smokable tobacco products through selective handling of strip tobacco based on particle size and shape. However, none of these patents teach a process or method for selectively removing the veins from the lamina.